Artistic display of general stellar currents in the Milky Way. Credit: NASA / JPL-Caltech / R. Hurt, SSC and Caltech
Examination of Theia 456 discovered that approximately 500 stars were born at the same time.
The Milky Way It houses 8,292 recently discovered star streams – all called Theia. But Theia 456 is special.
A stellar stream is a rare linear – rather than clustered – pattern of stars. After combining multiple data sets captured by the Gaia Space Telescope, a team of astrophysicists found that all 468 of Theia’s 456 stars were born at the same time and travel in the same direction across the sky.
Jeff Andrews A. Most star clusters form together. Northwestern University Astrophysicist and team member. “What’s interesting about Theia 456 is that it’s not a small group of stars together. It’s long and stretchy. There are relatively few streams close and young and scattered widely.”
Andrews presented this research during a hypothetical press conference at the 237th meeting of the American Astronomical Society. Theia 456: A Stellar Association in the Galactic Disk took place on January 15, 2021, as part of a session on the “Modern Milky Way”.
Andrews is a postdoctoral fellow at the Northwestern Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA). He conducted this work with astrophysicists Marcel Aguerus and Jason Curtis Columbia UniversityJulio Chanami of the University of Pontifica Cattolica, Simon Schuller of the University of Tampa, Kevin Covey and Marina Kunkel of Western Washington University.
While researchers have long known that stars form in groups, most known clusters are spherical in shape. It is only recently that astrophysicists began to find new patterns in the sky. They believe that the long strings of stars were once narrow clusters, gradually torn apart and stretched by tidal forces.
“As we started to get more advanced in our hardware, technology, and ability to extract data, we found that stars are in more structures than clusters,” Andrews said. “Often they form streams across the sky. Although we’ve known about these for decades, we have started to find hidden objects.”
Theia 456 spans more than 500 light-years, and is one of those hidden currents. Since it dwells within the galactic plane of the Milky Way, it is easily lost within the galactic background of 400 billion stars. Most of the stellar currents are found elsewhere in the universe – by telescopes directed away from the Milky Way.
“We tend to focus our telescopes in other directions because it’s easier to find things,” Andrews said. “Now we’re starting to find these currents in the galaxy itself. It’s like finding a needle in a haystack. Or, in this case, finding a ripple in the ocean.”
Defining and examining these structures is a challenge to data science. Artificial intelligence algorithms combed huge datasets of stellar data in order to find these structures. Andrews then developed algorithms to refer this data to pre-existing catalogs of the iron abundance of the stars documented.
Andrews and his team found that 468 stars within Thia 456 had a similar abundance of iron, which means that – 100 million years ago – the stars would likely have formed together. To add more evidence to this finding, the researchers examined a dataset of light curves, which captures how the brightness of the stars changes over time.
We are starting to find these currents in the Milky Way itself. It’s like finding a needle in a haystack. Or, in this case, finding an ocean ripple – Geoff Andrews, astrophysicist
“This can be used to measure the speed of rotation of stars,” Agüeros said. “Stars of the same age should show a distinct pattern in their rotation rates.”
With the help of data from NASAThe transiting satellite for exoplanet reconnaissance and from the Zwicky Transit Facility – both of which produced light curves for the stars in Thia 456 – Andrews and colleagues were able to determine that stars in the stream share a common lifetime.
The team also found that the stars move together in the same direction.
“If you know how the stars move, you can step back to see where the stars are,” Andrews said. “As we turned back the clock, the stars became closer and closer together. Therefore, we believe that all of these stars were born together and have a common origin.”
Andrews said combining data sets and data mining is essential to understanding the universe around us.
He said, “You can only reach this limit using one dataset.” “When you combine data sets, you get a richer sense of what’s in the sky.”
